An effective scheme for QoS estimation via alternating direction method-based matrix factorization

Accurately estimating unknown quality-of-service (QoS) data based on historical records of Web-service invocations is vital for automatic service selection. This work presents an effective scheme for addressing this issue via alternating direction method-based matrix factorization. Its main idea consists of a) adopting the principle of the alternating direction method to decompose the task of building a matrix factorization-based QoS-estimator into small subtasks, where each one trains a subset of desired parameters based on the latest status of the whole parameter set; b) building an ensemble of diversified single models with sophisticated diversifying and aggregating mechanism; and c) parallelizing the construction process of the ensemble to drastically reduce the time cost. Experimental results on two industrial QoS datasets demonstrate that with the proposed scheme, more accurate QoS estimates can be achieved than its peers with comparable computing time with the help of its practical parallelization.This work was supported in part by the FDCT (Fundo para o Desenvolvimento das Ciências e da Tecnologia) under Grant119/2014/A3, in part by the National Natu-ral Science Foundation of China under Grant 61370150, and Grant 61433014; in part by the Young Scientist Foun-dation of Chongqing under Grant cstc2014kjrc-qnrc40005; in part by the Chongqing Research Program of Basic Re-search and Frontier Technology under Grant cstc2015jcyjB0244; in part by the Postdoctoral Science Funded Project of Chongqing under Grant Xm2014043; in part by the Fundamental Research Funds for the Central Universities under Grant 106112015CDJXY180005; in part by the Specialized Research Fund for the Doctoral Pro-gram of Higher Education under Grant 20120191120030

Outlier-Resilient Web Service QoS Prediction

The proliferation of Web services makes it difficult for users to select the most appropriate one among numerous functionally identical or similar service candidates. Quality-of-Service (QoS) describes the non-functional characteristics of Web services, and it has become the key differentiator for service selection. However, users cannot invoke all Web services to obtain the corresponding QoS values due to high time cost and huge resource overhead. Thus, it is essential to predict unknown QoS values. Although various QoS prediction methods have been proposed, few of them have taken outliers into consideration, which may dramatically degrade the prediction performance. To overcome this limitation, we propose an outlier-resilient QoS prediction method in this paper. Our method utilizes Cauchy loss to measure the discrepancy between the observed QoS values and the predicted ones. Owing to the robustness of Cauchy loss, our method is resilient to outliers. We further extend our method to provide time-aware QoS prediction results by taking the temporal information into consideration. Finally, we conduct extensive experiments on both static and dynamic datasets. The results demonstrate that our method is able to achieve better performance than state-of-the-art baseline methods.Comment: 12 pages, to appear at the Web Conference (WWW) 202